When researchers put a group of men and women on a “lie diet,” they reported fewer health and mental-health complaints. The truth-tellers were more confident and comfortable in their personal relationships, which was statistically linked to a feeling of better health. (Also, keeping up lies is a mental stressor, according to one theory, and it seems like the truth-tellers knocked that out of their lives.)

But one tactic that seems to work is to ask a suspected fibber to repeat their story in reverse. Lying makes more work for your mind than telling the truth, so piling on an unusual additional task can lead liars to betray themselves through body language or other behavioral signs. Or, you could ask them to draw a picture. Unprepared for this task, liars turn out drawings with less detail than people who are telling the truth.